Allow RSA 4096 key in package verification

The RSA_verify sitll works for 4096 bits keys. And we just
need to loose the check on modulus.

Sample commands to generate the key & package:
1. openssl genrsa -out keypair.pem 4096
2. openssl pkcs8 -topk8 -inform PEM -outform DER -nocrypt \
   -in keypair.pem -out private.pk8
3. openssl req -new -x509 -key keypair.pem -out public.x509.pem \
   -days 365
4. java -Djava.library.path=prebuilts/sdk/tools/linux/lib64 -jar \
   prebuilts/sdk/tools/lib/signapk.jar -w public.x509.pem private.pk8 \
   unsigned.zip signed.zip

Bug: 129163830
Test: unit tests pass
Change-Id: I5a5ff539c9ff1955c02ec2ce4b17563cb92808a4
diff --git a/tests/component/verifier_test.cpp b/tests/component/verifier_test.cpp
index c904cd0..bdb8af2 100644
--- a/tests/component/verifier_test.cpp
+++ b/tests/component/verifier_test.cpp
@@ -158,6 +158,17 @@
   VerifyPackageWithSingleCertificate("otasigned_v5.zip", std::move(cert));
 }
 
+TEST(VerifierTest, LoadCertificateFromBuffer_sha256_rsa4096_bits) {
+  Certificate cert(0, Certificate::KEY_TYPE_RSA, nullptr, nullptr);
+  LoadKeyFromFile(from_testdata_base("testkey_4096bits.x509.pem"), &cert);
+
+  ASSERT_EQ(SHA256_DIGEST_LENGTH, cert.hash_len);
+  ASSERT_EQ(Certificate::KEY_TYPE_RSA, cert.key_type);
+  ASSERT_EQ(nullptr, cert.ec);
+
+  VerifyPackageWithSingleCertificate("otasigned_4096bits.zip", std::move(cert));
+}
+
 TEST(VerifierTest, LoadCertificateFromBuffer_check_rsa_keys) {
   std::unique_ptr<RSA, RSADeleter> rsa(RSA_new());
   std::unique_ptr<BIGNUM, decltype(&BN_free)> exponent(BN_new(), BN_free);
diff --git a/tests/testdata/otasigned_4096bits.zip b/tests/testdata/otasigned_4096bits.zip
new file mode 100644
index 0000000..5016dfc
--- /dev/null
+++ b/tests/testdata/otasigned_4096bits.zip
Binary files differ
diff --git a/tests/testdata/testkey_4096bits.x509.pem b/tests/testdata/testkey_4096bits.x509.pem
new file mode 100644
index 0000000..cba30d6
--- /dev/null
+++ b/tests/testdata/testkey_4096bits.x509.pem
@@ -0,0 +1,35 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/verifier.cpp b/verifier.cpp
index 68a011e..08d852b 100644
--- a/verifier.cpp
+++ b/verifier.cpp
@@ -373,8 +373,8 @@
   const BIGNUM* out_e;
   RSA_get0_key(rsa.get(), &out_n, &out_e, nullptr /* private exponent */);
   auto modulus_bits = BN_num_bits(out_n);
-  if (modulus_bits != 2048) {
-    LOG(ERROR) << "Modulus should be 2048 bits long, actual: " << modulus_bits;
+  if (modulus_bits != 2048 && modulus_bits != 4096) {
+    LOG(ERROR) << "Modulus should be 2048 or 4096 bits long, actual: " << modulus_bits;
     return false;
   }
 
diff --git a/verifier.h b/verifier.h
index 106b86b..ef9feaf 100644
--- a/verifier.h
+++ b/verifier.h
@@ -88,7 +88,8 @@
 //  VERIFY_FAILURE (if any error is encountered or no key matches the signature).
 int verify_file(VerifierInterface* package, const std::vector<Certificate>& keys);
 
-// Checks that the RSA key has a modulus of 2048 bits long, and public exponent is 3 or 65537.
+// Checks that the RSA key has a modulus of 2048 or 4096 bits long, and public exponent is 3 or
+// 65537.
 bool CheckRSAKey(const std::unique_ptr<RSA, RSADeleter>& rsa);
 
 // Checks that the field size of the curve for the EC key is 256 bits.